Select another layer in Layer Stack will trigger the live output media layer stop

Hi, I'm using Version 4.2.1(25918)
First add two source and two layer, each have one media file like mp4.
Then select a media file layer in Layer Stack panel, make it live, the media file will start play in program output.
Now, if I select the other layer in Layer Stack panel, the output media file will stop play.
Is that right?
Thanks.